The Curious Case of DNA Fingerprinting

The technique of determining an individual’s DNA traits is known as DNA profiling (also known as DNA fingerprinting). DNA barcoding is a type of DNA analysis that is used to identify a species rather than an individual.DNA fingerprinting is a method of extracting and identifying variable regions within the base-pair sequence of DNA. It is also known as DNA typing, DNA profiling, genetic fingerprinting, genotyping, or identification testing (deoxyribonucleic acid)

In criminal investigations, DNA profiling is a forensic approach that compares criminal suspects’ profiles to DNA evidence to determine the likelihood of their involvement in the crime. DNA profiling has been used to analyse animal and plant populations in the fields of zoology, botany, and agriculture. It’s also utilised in paternity testing, determining immigration eligibility, genealogical and medical research, and paternity testing.

Principles of DNA Fingerprinting

The fundamentals of DNA fingerprinting are as follows:

• Every human being on the planet has 99.9% of the same DNA. In each individual, however, about 0.1 percent of DNA or 3 x 106 base pairs (out of 3 x 109 bp), is unique.
• The human genome contains several short non-coding yet inheritable base sequences that are repeated multiple times called the “junk DNA.”  They don’t code for proteins, but they make up 95 percent of our genetic DNA.
• They are dubbed satellite DNA because they may be isolated from the bulk DNA as satellites during density gradient centrifugation.
• Polymorphism can be found in satellite DNA. When a variant at a locus occurs with a frequency of more than 0.01 population, the word polymorphism is used.
• Bases are repeated in tandem in satellite DNA. Satellite DNAs are divided into microsatellites and minisatellites based on their length, base makeup, and several tandemly repeating units.
• Mutations result in variations. These non-coding sequence mutations have accumulated throughout time and are the source of DNA polymorphism (variation at the genetic level arises due to mutations).
• The length polymorphisms that make up the junk DNA sections show variances in the physical length of the DNA molecule.
• The number of tandem repeats at specific chromosome locations varies from person to person. For each given locus on the chromosome, there will be a set number of repeats.
• The repeat regions are divided into two groups based on the size of the repeat. A variable number of tandem repeats (VNTRs) have repeats of 9-80 base pairs, while short tandem repeats (STRs) have repeats of 2-5 base pairs.
• When DNA from a single person is digested with a restriction enzyme, distinct fragment patterns (sizes) and cleavage site positions are produced.

Application of DNA Fingerprinting

The groundbreaking DNA fingerprinting approach has numerous implications in sectors ranging from forensics to medicine.

• Revealing a person’s identity: Biological identity is the only thing that distinguishes a human or any life on the planet. The biological identity of a person can be discovered through DNA analysis.

• Identifying dead bodies: The approach aids in the identification of bodies that have been severely injured.

• Identification of blood relatives: The current method has been used to determine or determine the blood link between two unrelated persons. The examiner takes biological samples from two people, either parents or children, obtains DNA, runs a test, and analyses the results. The results determine whether or not the samples are from blood relatives.

• Organ transplantation studies: In the event of organ transplantation, one of the essential applications of DNA profiling is to monitor graft acceptance and rejection. For transplantation investigations, the HLA typing approach has been used. Human Leukocyte Antigens (HLAs) have a role in the immune system. For graft and transplantation studies, many HLA loci are investigated. Graft acceptance is indicated by the precise match score. This signifies that the organ can be transplanted.

Process of DNA fingerprinting

The primary steps include sample collection, DNA extraction, digestion or amplification, and analysis outcomes.

• Step 1: Sample collection
  We can extract DNA from any bodily fluid or sample. The most common types of samples used are buccal smears, saliva, blood, amniotic fluid, chorionic villi, skin, hair, body fluid, and other tissues. A buccal swab is routinely taken in criminal proceedings. The buccal swab sample collection procedure is simple and non-invasive.

• Step 2: DNA Extraction

One of the most important processes in any genetic application is DNA extraction. The chances of receiving favourable outcomes are increased when the DNA is of good quality and quantity.

• Step 3: Selecting a technique
  The procedure of selecting a technique depends on the experiment; for example, for detecting maternal cell contamination, PCR-based gel electrophoresis is sufficient. Forensic analysis, on the other hand, uses capillary gel electrophoresis and real-time PCR. Various types of techniques are RFLP, PCR-agarose gel electrophoresis, RT-PCR, DNA Sequencing, Capillary electrophoresis.

• Step 4: Result and Interpretation
  Information about individual differences and similarities can be gained by comparing the DNA profiles of distinct samples. It’s worth noting that the entire procedure is now nearly automated.

Conclusion

One of the most powerful identification technologies we have for recognising an individual or live entity is DNA fingerprinting. Except for identical twins, triplets, and other genetically similar creatures, every living thing is genetically unique in its way. Each individual has a distinct sequence that is unique to that particular organism. Unlike traditional fingerprints, which may be surgically altered or self-mutilated, the DNA sequence can’t be modified once it’s left at a crime scene, making it more useful in forensics and boosting the chances of discovering an exact match. DNA, also known as deoxyribonucleic acid, is made up of a unique sequence of bases called nucleotides that hold all of the information about a live organism’s properties.